Cnloader valve



April 23, 1935.

c. E. PLOEGER,

UNLOADER VALVE Original Filed July 14, 1931 Res-ma 23, loss umrrso STATES PATENT OFFICE Servel, Inc., New York, N.

Delaware Y., a corporation of Original No. 1,912,463, dated June 6, 193$,8erial I i No. 550,643, July 14, 1931.

pplication for reilslle August 21, 1934, Serial No. 740,838

ZClaims.

This invention relates to unloaders for electric motors and more particularly to automatic control of an unloading device by electromagnetic means in the starting circuit of an electric motor.

An object of this invention is to provide an electromagnetic device in the starting ,circuit of a single phase motor for relieving the latter of its load during the starting period. In a compressor driven by an electric motor as in the condensing unit of compression type refrigerating apparatus, it is desirable to relieve the compressor load during the starting period of the driving motor and this is usually accomplished by providing a normally closed pressure relief or unloading valve on the discharge side of the compressor which is opened during the starting period, that is until the motor reaches its normal running In accordance with this invention a single phase induction motor is provided with an electromagnetic device in the motor circuit which is ccmnected to open an unloading valve on the compressor to relieve the load during the starting period of the motor. In one embodiment of this invention a solenoid is arranged to open an unloading valve and is connected in series with the starting winding of a single phase motor, whereby the solenoid is energized to open the valve when the starting winding circuit is closed by any well knownmeanssuchasarelayin the mainor running winding circuit. This invention is also applicable to a capacitor type single phase motor, in

which application the electromagnetic unloadins" I device is connected to be energized when the connections to the phase shifting circuit are changed upon operation of'a relay which is connected in the main or running winding circuit of the motor.

This invention will be more fully understood by reference to the following description taken in connection with the accompanying drawing wherein a Fig. 1 is a diagram of connections showing this invention applied to a single phase induction motor of the split phase starting type; and

Fig. 2 is a diagram of connections showing this invention applied to a single phase induction motor of the capacitor type. a In Fig. 1 of the drawing reference numeral I designates the running winding of a single phase alternating current motor. One end of. the startingwindinglisconnectedtotherunning winding I and the line I of the source of current supply. The relay solenoid I is connected in series 'withthe motor winding I and the current supply line 0. The armature l which is operatively associated with the relay solenoid I is also connected to the lineand a normally open contact I which is associated with this armature is connected to the winding I of an electromagnetically operated load-relieving apparatus. The winding 1 is connected in series with the starting winding 2 of the motor.

In operation, the initial current flow through the running winding l and the solenoid 3 is relatively large andcauses the solenoid 3 to lift the armature 4, whereupon the contact 9 is closed and the circuit between the starting winding 2 of the motor and the line -6 is completed. A relatively large initial current also flows through the winding 2. The solenoid I, which is connected in series with the winding 2, lifts the valve I and thereupon relieves the load on the motor until the solenoid I is deenergized which occurs when the current through the motor winding l decreases to the normal or running valve and the magnetic field set up by this current in the solenoid I is of insufllcient intensity to retain the armature I.

The valve I may, by way of example, be positioned on the discharge side of a compressor which is operated by the motor, This valve is maintained closed by its own weight and atmospheric pressure acting upon it. Additional springs bearing down upon this valve may also be provided when it is employed in positions where forces of gravity would tend to maintain it in open position.

In Fig. 2 of the drawing another form of this invention in which the main winding ll of a capacitor type of alternating current single phase motor is connected in series with the relay winding l3 across the source of current supply lines ll-li. The capacitor winding I! of the motor is connected directly to the winding I l and the line II. The armature II, which is operatively associated with the solenoid II, is connected directly to the line it. One ofcthe contacts II of the relay armature II is connected in series with the load relieveing solenoid I1 and the common connection of the motor windings II and I2 and the line ll. One oi the contacts ll of the armature I4 is connected at tap I! of the inductance 22 which, together with the condenser 23,- forms the phase-shifting circuit. Tap ll of the inductance 22 is connected to one oi the contacts II. A connection is also provided between the capacitor winding l2 and the phase-shifting circuit which includes inductance I2 and condenser Il.

The contacts" "and II are closed when the ing ll of the motor is established for starting the motor, since the initial current flow through the solenoid II is relatively large and the magnetic field set up by this current in the mag etic circuit of this solenoid is suiilcient to lift the armature it. The solenoid i1 is thus connected across the source of current supply lines I! and I6 and the capacitor winding 12 is connected through the point 24 of the inductance 22 and the contacts 20 to the line Ii. The circuit between the contacts l9 and the tap 2' of the inductance 22 is simultaneously broken.

When the solenoid I1 is connected to the lines l5 and 16 the valve Ii, which is connected into the low pressure side of a gas compressor, is

' opened electromagnetically and the motor, with which the windings Ii and I! are operatively associated, is relieved of its gas compressor or similar load. At the same time the line I! connected to the inductance 22 is shifted from point 25 to point 24. This causes a substantial shift in the phase relation between the current energizing winding I! and the current energizing winding II. A rotating electromagnetic fleld is thus set up in the motor windings for the purpose of starting the motor. After the motor attains a certain speed the line current through the solenoid II and the winding I l decreases to a low-- or value and the armature ll isreleased,inasmuch as this armature is adjusted to require a relatively large magnetic force, such is set up in the solenoid by the motor starting current, to retain it in its upper position. The contacts I! are then 19,544 circuit between the lines ll and n and the windclosed and the phase-shifting circuit 22, a connected as adjusted for running conditions.

It will be obvious to those skilled in the art that various other changes may be made in the construction and arrangement without departing from the spirit of the invention and therefore the invention is not limited to what is described in the specification and shown in the drawing but only as indicated in the appended claims.

I claim: 1. In combination, an electric motor having a running winding and a phase-distorting winding arranged to be energized in parallel from a source of current supply, a first solenoid connected in series with said running winding, a second solenoid connected. in series with only said phase-distorting winding, said first solenoid being connected to close the circuit of said phase-distorting winding and. said second solenoid for starting said motor, and means associated with said second solenoid forrelieving the load of said motor during starting.

2. In combination, an electric motor adapted for operation from a single phase alternating current source of supply, running and starting windingspperatively associated with said motor,

solenoids connected in series with said winding one of said solenoids being connected to control the circuit of said starting winding during the 1 starting of said motor, and a valve operable by a second of said solenoids, said second solenoid being only in the circuit of said starting windin and operative to operate said valve to relieve 581! motor of its load during starting.

, CLYDE E. PLOEGER. 

